Sludge cleaning agent

Abstract

To provide a sludge cleaning agent that enables cleaning and removal of sludge deposited in a fuel oil system using a marine fuel oil (VLSFO) having a sulfur content of 0.5 mass% or less.SOLUTION: The sludge cleaning agent of the present invention is a sludge cleaning agent for a fuel oil system. The fuel oil is a marine fuel oil having a sulfur content of 0.5 mass% or less and comprises N-methyl-2-pyrrolidone and a hydrocarbon solvent, thereby making it possible to clean and remove sludge deposited in the fuel oil system using a marine fuel oil (VLSFO) having a sulfur content of 0.5 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a sludge cleaning agent, and more particularly to a cleaning agent that removes sludge deposited in a fuel oil system using marine fuel oil with a sulfur content of 0.5% by mass or less. [Background technology]

[0002] A fuel oil system is a device that consists of various devices such as oil purifiers, pumps, flow meters, air separators, heaters, and viscosity adjustment devices, connected by pipes and valves.In addition to removing impurities from fuel oil that could damage engines and generators, the system also uses heaters and pumps to adjust the fuel oil's dynamic viscosity and flow rate, making the fuel oil combustible and supplying it to engines and generators.

[0003] In such fuel oil systems, if sludge accumulates, it will not only reduce the cleaning ability of the oil purifier, but will also cause blockages in pipes and valves and malfunctions in the fuel oil tank, so it is necessary to remove sludge that has accumulated in the fuel oil purification system and fuel oil transfer system.

[0004] The process by which the sludge is produced and its specific composition are not clear, but it is composed of hydrocarbon substances such as asphaltene contained in crude oil and wax formed when paraffin crystallizes and precipitates.

[0005] Known cleaning agents for removing the sludge include a cleaning agent that combines a chelating agent and a water-soluble solvent (Patent Document 1), a cleaning agent that solubilizes or emulsifies a chelating agent and a hydrocarbon solvent (Patent Document 2), and a cleaning agent that combines a chlorine-based solvent, an acid, and a glycol-based solvent (Patent Documents 3 and 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 62-153400 [Patent Document 2] Japanese Patent Application Publication No. 63-33498 [Patent Document 3] Japanese Unexamined Patent Publication No. 48-5807 [Patent Document 4] Japanese Unexamined Patent Publication No. 48-5808 Summary of the Invention [Problem to be solved by the invention]

[0007] However, with regard to marine fuel oil, the International Maritime Organization (IMO) has decided to significantly reduce the sulfur content, and from 2020, marine fuel oil will be switched from high sulfur heavy fuel oil (HSHFO), which has a sulfur content of 3.5% by mass or less, to very low sulfur fuel oil (VLSFO), which has a sulfur content of 0.5% by mass or less.

[0008] The above-mentioned marine fuel oil (VLSFO) with a sulfur content of 0.5% by mass or less not only has a lower sulfur content than conventional HSHFO, but also has properties that differ from HSHFO, such as a low kinematic viscosity at room temperature (25°C), but a high pour point, causing it to gel and lose fluidity at around 4°C.As a result, conventional sludge cleaning agents are unable to adequately clean the sludge that accumulates in fuel oil systems that use VLSFO.

[0009] The present invention has been made in view of the problems associated with the prior art, and an object of the present invention is to provide a sludge cleaning agent that can clean and remove sludge accumulated in a fuel oil system that uses very low-sulfur marine fuel oil (VLSFO) with a sulfur content of 0.5% by mass or less. [Means for solving the problem]

[0010] The inventors observed the sludge derived from VLSFO after cleaning with a conventional sludge cleaner and confirmed that a hard coating with little oil content had been formed.

[0011] This is thought to be because VLSFO has a low kinetic viscosity, and asphaltene sludge with low oil content and hard dry sludge tend to settle and are difficult to resuspend, so they accumulate one after another on the separation plates and piping of the oil purifier, increasing their adhesive strength and causing them to adhere firmly.

[0012] The present inventors have discovered that the above object can be achieved by not only dissolving the sludge but also peeling off the coating of the sludge, and have thus completed the present invention.

[0013] That is, the above problems are solved by the following (1) to (5) of the present invention. (1) A sludge cleaning agent for a fuel oil system, comprising: The fuel oil is a marine fuel oil having a sulfur content of 0.5% by mass or less, A sludge cleaning agent comprising N-methyl-2-pyrrolidone and a hydrocarbon solvent. (2) The sludge cleaning agent according to the above item (1), characterized in that the content of N-methyl-2-pyrrolidone is 3% by mass to 30% by mass. (3) The sludge cleaning agent according to the above item (1), wherein the hydrocarbon solvent contains an aromatic hydrocarbon solvent. (4) The sludge cleaning agent according to the above item (1), further comprising a surfactant. (5) The sludge cleaning agent according to the above item (1), further comprising a glycol ether solvent. [Effects of the Invention]

[0014] According to the present invention, since N-methyl-2-pyrrolidone and a hydrocarbon solvent are mixed, it is possible to provide a sludge cleaning agent that can clean and remove sludge deposited in a fuel oil system that uses very low-sulfur marine fuel oil (VLSFO) with a sulfur content of 0.5 mass% or less. DETAILED DESCRIPTION OF THE INVENTION

[0015] The sludge cleaning agent of the present invention will now be described in detail. The sludge cleaning agent of the present invention is a cleaning agent for sludge that has accumulated in a fuel oil system that uses marine fuel oil with a sulfur content of 0.5 mass % or less, and contains N-methyl-2-pyrrolidone and a hydrocarbon solvent.

[0016] The reason why the sludge cleaning agent of the present invention can clean sludge derived from VLSFO has not been completely clarified, but can be presumed as follows.

[0017] N-methyl-2-pyrrolidone is a highly polar solvent and is not compatible with non-polar mineral oils, so it is not expected to dissolve sludge at all. However, it is used as a paint stripper.

[0018] The sludge cleaning agent of the present invention contains N-methyl-2-pyrrolidone, making it possible to remove the film of VLSFO-derived sludge that has firmly adhered to the separation plates and piping of oil purifiers.

[0019] The sludge cleaning agent of the present invention contains a hydrocarbon solvent in addition to N-methyl-2-pyrrolidone, which is believed to dissolve the peeled sludge film and prevent the peeled sludge film from re-accumulating and adhering to the surface.

[0020] As the hydrocarbon solvent, a hydrocarbon containing 10 mass % or more of a fraction at 100 to 350° C. that dissolves asphaltene can be used.

[0021] Asphaltene is generally defined as a component that is insoluble in heptane and soluble in toluene. Examples of hydrocarbon solvents that can dissolve asphaltene include petroleum fractions such as kerosene and diesel, paraffinic hydrocarbons, naphthenic hydrocarbons, and aromatic hydrocarbons such as toluene, xylene, trimethylbenzene, and naphthalene. Of these, aromatic hydrocarbon solvents are preferred.

[0022] The sludge cleaning agent preferably contains N-methyl-2-pyrrolidone and hydrocarbon solvent in a ratio of 3 to 30% by mass / 97 to 70% by mass (N-methyl-2-pyrrolidone / hydrocarbon solvent), and more preferably contains 12 to 22% by mass of N-methyl-2-pyrrolidone.

[0023] By including 3 to 30 mass % of N-methyl-2-pyrrolidone, the coating of sludge derived from VLSFO can be peeled off and removed.

[0024] The sludge cleaning agent of the present invention may contain a surfactant, if necessary. The inclusion of a surfactant improves wetting and penetration of sludge and carbon, improving the cleaning effect.

[0025] As the surfactant, any of nonionic surfactants, amphoteric surfactants, cationic surfactants and anionic surfactants can be used, and these can be used alone or in combination.

[0026] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, polyoxyethylene styrenated phenol ethers, sorbitan fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil, polyoxyethylene alkylamines, alkanolamides, and glycerin fatty acid esters.

[0027] Examples of cationic surfactants include quaternary ammonium salts and fatty acid amidoamines, and examples of anionic surfactants include alkyl sulfates, fatty acid salts, sulfonates, sulfosuccinates, polyoxyethylene alkyl ether sulfates, alkylbenzenesulfonates, polyoxyethylene alkyl sulfosuccinates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether phosphates (salts), polyoxyethylene styrenated phenyl ether sulfates, and naphthalenesulfonate formalin condensates.

[0028] Examples of amphoteric surfactants include alkyl betaines, fatty acid amidoamine betaines, and alkylamine oxides.

[0029] Among these, polyoxyethylene alkyl ethers and polyoxyalkylene alkyl ethers having an HLB of 2 to 15 are preferred because they have excellent wettability and permeability to sludge.

[0030] The content of the surfactant is preferably 0.1 to 5.0% by mass, and more preferably 0.2 to 3.0% by mass.

[0031] The sludge cleaning agent of the present invention can also contain a glycol ether solvent. The glycol ether solvent acts as a solubilizer for water-containing sludge, inhibiting sludge re-adhesion and contributing to the long-term stability of the sludge cleaning agent. Furthermore, the blending ratio of N-methyl-2-pyrrolidone can be reduced, thereby reducing costs.

[0032] As the glycol ether solvent, ethylene glycol ether and propylene glycol ether can be used.

[0033] Examples of ethylene glycol ethers include diethylene glycol methyl ether, triethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol ethyl ether, ethylene glycol n-butyl ether, diethylene glycol n-butyl ether, triethylene glycol n-butyl ether, ethylene glycol hexyl ether, diethylene glycol hexyl ether, ethylene glycol n-butyl ether acetate, diethylene glycol n-butyl ether acetate, and ethylene glycol phenyl ether.

[0034] Examples of propylene glycol ethers include propylene glycol methyl ether, diethylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, propylene n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol diacetate, and propylene glycol phenyl ether.

[0035] Of these, ethylene glycol n-butyl ether, diethylene glycol n-butyl ether, ethylene glycol n-butyl ether acetate, ethylene glycol phenyl ether, and propylene glycol phenyl ether are preferably used.

[0036] The content of the glycol ether solvent is preferably 1.0 to 15.0% by mass, and more preferably 2.0 to 10.0% by mass. [Example]

[0037] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0038] A sludge cleaning agent with the composition shown in Table 1 was prepared, and an oil purifier separation plate and a secondary backwash strainer element to which sludge derived from very low sulfur fuel oil (VLSFO) had firmly adhered were immersed in the sludge cleaning agent at room temperature for 24 hours, and the remaining sludge was observed and evaluated according to the following criteria. The oil purifier separation plate was lightly wiped with a cloth, and the secondary backwash strainer element was rinsed with washing oil before observation. ◎: Sludge was completely removed (80% or more). 〇: Almost completely removed (60% to less than 80%). △: A significant amount remains (30% to less than 60% removed). ×: Almost no removal (less than 30% removal).

[0039] [Table 1]

[0040] Comparative Examples 8 to 11 show that sludge cleaning agents using chlorinated solvents or acids, which have been used conventionally as sludge cleaning agents, are unable to sufficiently clean sludge derived from very low sulfur fuel oil (VLSFO).

[0041] Comparison of Comparative Examples 1 and 6 with each Example shows that in order to exert detergency against sludge derived from very low sulfur fuel oil (VLSFO), it is necessary to contain both N-methyl-2-pyrrolidone and a hydrocarbon solvent.

[0042] Comparison of Comparative Examples 2 to 5 with each Example shows that the sludge cleaning agent containing N-methyl-2-pyrrolidone has superior detergency for sludge derived from very low sulfur fuel oil (VLSFO) compared to cleaning agents containing other polar organic solvents.

[0043] Comparison of Example 3 with Example 4 and Example 5 with Example 6 shows that when the hydrocarbon solvent is an aromatic hydrocarbon solvent, the detergency for sludge derived from very low sulfur fuel oil (VLSFO) is excellent.

[0044] A comparison of Examples 4, 7, and 10 shows that by including a glycol ether solvent, the same effect can be obtained even if the content of N-methyl-2-pyrrolidone is reduced, and costs can be reduced.

Claims

1. 1. A sludge cleaning agent for a fuel oil system, comprising: The fuel oil is a marine fuel oil having a sulfur content of 0.5% by mass or less, A sludge cleaner comprising N-methyl-2-pyrrolidone and a hydrocarbon solvent.

2. 2. The sludge cleaning agent according to claim 1, wherein the content of N-methyl-2-pyrrolidone is 3% by mass to 30% by mass.

3. 2. The sludge cleaning agent according to claim 1, wherein the hydrocarbon solvent contains an aromatic hydrocarbon solvent.

4. 2. The sludge cleaning agent according to claim 1, further comprising a surfactant.

5. 2. The sludge cleaning agent according to claim 1, further comprising a glycol ether solvent.

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